package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 */
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;//全局唯一订单id
    @Resource
    private RedissonClient redissonClient;
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }


    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    //PostConstruct 类实例化之后自动调用，启动一个线程来处理订单
    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    //消息队列
    private class VoucherOrderHandler implements Runnable{

        String queueName = "stream.orders";
        @Override
        public void run() {
            while (true) {
                try {
                    //1.获取队列中的订单信息 XREADGROUP group g1 c1 COUNT 1 BLOCK 2000 STREAMS stream.orders
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    //2.判断消息获取是否成功
                    if (list == null || list.isEmpty()){
                        //2.1.获取失败，说明没有消息，继续下一次循环
                        continue;
                    }
                    //3.解析消息中的订单信息
                    parseOrderInformation(queueName, list);
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    handlePendingList();
                }
            }
        }

        /**
         * 未ack确认，从pendingList取处理
         */
        private void handlePendingList() {
            String queueName = "stream.orders";
            while (true) {
                try {
                    //1.获取pending-list中的订单信息 XREADGROUP group g1 c1 COUNT 1 STREAMS stream.orders
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );

                    //2.判断消息获取是否成功
                    if (list == null || list.isEmpty()){
                        //2.1.获取失败，说明没有消息，退出循环
                        break;
                    }

                    //3.解析消息中的订单信息
                    parseOrderInformation(queueName, list);
                } catch (Exception e) {
                    log.error("处理pending-list订单异常", e);
                    try {
                        Thread.sleep(30);
                    } catch (InterruptedException ex) {
                        ex.printStackTrace();
                    }
                }
            }

        }

        /**
         * 解析消息中的订单信息
         * @param queueName 队列名称
         * @param list 订单信息列表
         */
        private void parseOrderInformation(String queueName, List<MapRecord<String, Object, Object>> list) {
            for (MapRecord<String, Object, Object> record : list) {
                Map<Object, Object> values = record.getValue();
                VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);

                //3.获取成功 下单
                createVoucherOrder(voucherOrder);
                //4.ack确认
                stringRedisTemplate.opsForStream().acknowledge(queueName,"g1",record.getId());
            }
        }

    }

    /**
     * 一人一单 创建订单
     * @param voucherOrder 订单信息
     */

    public void createVoucherOrder(VoucherOrder voucherOrder) {
        //6.一人一单
        Long userId = voucherOrder.getUserId();
        Long voucherId = voucherOrder.getVoucherId();

        //创建锁对象
        RLock redisLock = redissonClient.getLock("lock:order:" + userId);
        //尝试获取锁
        boolean isLock = redisLock.tryLock();
        if (!isLock){
            log.error("不允许重复下单");
            return;
        }

        try {
            //6.1.查询订单
            long count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
            if (count > 0) {
                log.error("用户已经购买过一次");
                return;
            }

            //6.库存够，减库存
            boolean result = seckillVoucherService.update().setSql("stock = stock - 1")
                    .eq("voucher_id", voucherId)
                    .gt("stock", 0)
                    .update();
            if (!result) {
                log.error("库存不足");
                return;
            }
            //7.创建订单
            save(voucherOrder);
        } finally {
            redisLock.unlock();
        }
    }

    IVoucherOrderService proxy;


    /**
     * 处理秒杀请求主要入口 stream消息队列
     * @param voucherId 优惠券id
     * @return 返回订单id
     */
    @Override
    public Result seckillVoucher(Long voucherId) {
        //获取用户
        Long userId = UserHolder.getUser().getId();
        //获取订单id
        long orderId = redisIdWorker.nextId("order");
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString(),
                String.valueOf(orderId)
        );

        //2.判断结果是为0
        assert result != null;
        int r = result.intValue();
        if (r !=0 ){
            //2.1.不为0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        //获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();

        //3.返回订单id
        return Result.ok(orderId);
    }




    /**
     * 解决订单问题(并发安全) 阻塞队列
     * @param voucherOrder 订单信息
     */
    /*private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //获取用户id 不能再从UserHolder里取 因为是一个多线程 从线程池里获取了一个新线程 不是主线程去做
        Long userId = voucherOrder.getUserId();
        //获取锁对象
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        //获取锁
        boolean result = lock.tryLock();

        if (!result){
            //获取锁失败 异步处理 不用返回什么东西 理论不用加锁，因为在redis里已经判断了
            //再次加锁是为了兜底，虽然redis出现问题概率很低
            log.error("不允许重复下单");
            return;
        }
        try {
            //获取代理对象(事务)，这里是拿不到的 因为是子线程，无法从ThreadLocal里获取想要的 只能提前获取事务对象
            proxy.createVoucherOrder(voucherOrder);
        } finally {
            lock.unlock();
        }

    }*/

    //阻塞队列异步
    /*private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024*1024);
    private class VoucherOrderHandler implements Runnable{

        @Override
        public void run() {
            try {
                //1.获取队列中的订单信息
                VoucherOrder voucherOrder = orderTasks.take();
                //2.创建订单
                handleVoucherOrder(voucherOrder);
            }catch (Exception e){
                log.error("处理订单异常",e);
            }
        }
    }*/

    /**
     * 处理秒杀请求主要入口 阻塞队列
     */
    /*@Override
    public Result seckillVoucher(Long voucherId) {
        //获取用户
        Long userId = UserHolder.getUser().getId();
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString());

        //2.判断结果是为0
        assert result != null;
        int r = result.intValue();
        if (r !=0 ){
            //2.1.不为0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        //2.2.为0，有资格，把下单信息保存到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        //2.3.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //2.4.用户id
        voucherOrder.setUserId(userId);
        //2.5.代金券id
        voucherOrder.setVoucherId(voucherId);
        //2.6.放入阻塞队列
        orderTasks.add(voucherOrder);

        //获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();

        //3.返回订单id
        return Result.ok(orderId);
    }*/

    /*@Override
    public Result seckillVoucher(Long voucherId) {
        //1.查询优惠卷
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        //2.判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            //未开始
            return Result.fail("秒杀活动未开始");
        }
        //3.判断秒杀是否结束
        if( voucher.getEndTime().isBefore(LocalDateTime.now())){
            return Result.fail("秒杀活动已结束");
        }

        //4.开始，判断库存
        Integer stock = voucher.getStock();
        if (stock <= 0){
            //5.库存不够，返回异常
            return Result.fail("库存不足");
        }

        Long userId = UserHolder.getUser().getId();
        
        //获取锁对象
        //SimpleRedisLock lock = new SimpleRedisLock("order" + userId, stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        boolean isLock = lock.tryLock();
        //判断是否获取锁成功
        if (!isLock){
            return Result.fail("一人只允许下一单");
        }
        try {
            //获取代理对象(跟事务有关的)
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        } finally {
            lock.unlock();
        }

    }*/

    /**
     * 创建优惠券订单
     * @param voucherId 优惠券id
     * @return 订单id
     */
    /*@Transactional
    public Result createVoucherOrder(Long voucherId) {
        //6.一人一单
        Long userId = UserHolder.getUser().getId();

        //6.1.查询订单
        long count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
        if (count > 0) {
            return Result.fail("用户已经购买过一次");
        }

        //6.库存够，减库存
        boolean result = seckillVoucherService.update().setSql("stock = stock - 1")
                .eq("voucher_id", voucherId)
                .gt("stock", 0)
                .update();
        if (!result) {
            return Result.fail("库存不足");
        }
        //7.创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        //7.1.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //7.2.用户id
        voucherOrder.setUserId(userId);
        //7.3.代金券id
        voucherOrder.setVoucherId(voucherId);
        save(voucherOrder);

        //8.返回订单id
        return Result.ok(orderId);

    }*/
}
